Construction of Unsaturated Coordinated Cu-Metal-Organic Frameworks for Iodine Adsorption.

Radioactive iodine from nuclear energy poses serious risks to aquatic environments, driving the need for efficient adsorbents for nuclear wastewater treatment. Metal-organic frameworks (MOFs) have shown promise in iodine capture due to their tunable pores and functional surfaces. In this work, three copper-triazolate-based MOFs with unsaturated coordination (CuCl2(TRZ) for 1, Cu4OCl3(TRZ)3 for 2, Cu3HOCl2(TRZ)3·2.4H2O for 3; TRZ = 1,2,4-triazole) were synthesized and characterized. Compound 1 exhibits a one-dimensional chain structure, compound 2 exhibits a two-dimensional layer, and compound 3 exhibits a three-dimensional cage architecture featuring a 10 Å molecular cage with two kinds of window sizes at 5 and 7.8 Å, respectively. In the evaluation of iodine adsorption in aqueous solution, compound 3 demonstrated outstanding iodine adsorption, removing 95% of iodine from aqueous solution within 200 min and maintaining high efficiency and structural stability over four adsorption-desorption cycles. This study offers a new strategy for designing radioactive iodine adsorbents and enhances the understanding of interactions between unsaturated metal sites and iodine species.